Tweet

Jon Deeks

18 Jan, 11 tweets, 2 min read

Context matters … I am aware that people outside the UK are reading my tweets and papers, and influencing their thinking about lateral flow testing. It’s really important that you understand the context I am writing from, and why it probably is different where you are.

1/11

The situation and issues in the UK (particularly in England), is almost certainly unlike where you are. The UK Government are unique in many ways and that is impacting on how tests are being used. (As a Brit I am also prone to understatement and being overpolite).

2/11

Our Government have staked their reputation on the Moonshot idea “to get our lives back to normal” using LFTs before there was evidence to see whether it would work. It doesn’t make sense to decide policy before evaluating the technology. Decision-making is now politicised.
3/11

Some decisions made about testing here are bizarre, and I am tweeting in that context. It would be unfortunate if my tweets are misunderstood and then inappropriately influence decisions elsewhere. But my tweets are not false or wrong as has been implied.

4/11

The Government are making implementation decisions about LFTs (e.g. allowing visitors to care homes, allowing close contacts to remain at school) without there being supporting evidence, and contrary to advice from our regulator, professional associations and many others.

5/11

The Government are also providing confusing information to the public – for example every parent was sent a letter telling them LFTs were as good as finding cases as a PCR. And they were not been told that testing in schools is part of “an evaluation”

6/11

LFTs have some good uses, but there are applications where they are unlikely to work, mainly around using negative results to say people are “safe”. I am tweeting about those– and the misinformation surrounding them. My emphasis is these issues which are big in the UK
7/11

Also note in the UK we are using the Innova test. That isn’t because it is the best test – but because it was the first test (and currently the only test) to pass through field studies. Not all LFTs are the same and recent data on other LFTs are impressive.
8/11

I am not going to suggest what people do elsewhere in world. However I would suggest that you all evaluate, in good scientific studies, how well tests work in your settings. Be clear about the People, Places and Purpose for tests, think about the Alternatives and Compare.
9/11

The biggest hindrance to rational progress is the lack of good relevant empirical evidence. Get good scientists from all discplines together, get them to argue and listen to each other. Get peer review and scrutiny. Publish protocols and all findings to earn trust.
10/11

But remember tests can have unintended bad effects as well as good effects. Look out for all. And if it doesn’t work - stop. Don’t stake your reputation on something working – stake it on getting the good science done to find out.
11/11

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More from @deeksj

Jon Deeks

@deeksj

16 Jan

@educationgovuk

Testing in schools saga - again

What is the explanation behind this from @educationgovuk? Why has the @MHRAgovuk said DfE does not need regulatory approval for daily “assisted testing” given it does not approve daily “self testing” of contacts of infected cases in schools?

Daily self-testing of contacts was not approved because MHRA considered that the test misses too many cases, allowing infected and infectious individuals to remain in class. The MHRA would have come to this decision based on a forensic and balanced assessment of the evidence.

Hopefully somebody can help answer why this does not also apply to “assisted testing”. I can think of three different explanations. There may be more.

Read 7 tweets

Jon Deeks

@deeksj

15 Jan

https://twitter.com/ScienceShared/status/1350141171994144768

Great summary and we really need to take the toxicity out of this. Agree with >95% of what is here. Thx for taking time to do this. The big challenge is how we make quick progress without being able to get a ref std for infectiousness. Cluster RCTs great but hard to do.

https://twitter.com/ScienceShared/status/1350141171994144768

Part of my 5% disagreement arises in whether we are making a mistake in trying to force “infectiousness” into the test accuracy paradigm, or whether we could do better considering it in a different way. It is a probabilistic rather than binary concept which causes the problem.

We can classify people as more or less likely to infect others, but I don’t think we will ever successfully put people into two groups of those who do or do not infect somebody else from a test. That is unlike our ability to say that people do or not have detectable virus.

Read 9 tweets

Jon Deeks

@deeksj

15 Jan

@DHSCgovuk

The testing in schools story is still unfolding.

@DHSCgovuk told journalists today that yesterday's Guardian story was "not true".

But then the @MHRAgovuk have come and said the opposite.

schoolsweek.co.uk/rapid-covid-te…

The MHRA has now confirmed to Schools Week it has “not issued an Exceptional Use Authorisation for that self-test device for ‘serial testing’ for school pupils who have been exposed to a confirmed positive COVID case that would enable them to attend school as normal”.

MHRA: “continues to advise that close contacts of positive cases identified using the self test device continue to self-isolate in line with current guidelines. Discussions with Test and Trace regarding any future exceptional use cases are ongoing.”

So - contradicting DfE policy

Read 6 tweets

Jon Deeks

@deeksj

7 Jan

I'm rather concerned by the inability of Test-and-Trace to explain the diagnostic accuracy of the lateral flow test. This was the statement about the performance of Innova in the School Handbook sent out by Test-and-Trace before Xmas.

"As accurate in identifying as PCR" is simply not true. Specificity tells you about false positives, not true positives. It tells you the proportion of those without COVID who correctly get negative results. It doesn't tell you how could the test is at identifying cases.

And interesting that the high figure for specificity is stated, but no numbers for sensitivity are given (which are much lower - 40% in Liverpool). We don't want selective reporting from our Health Department.

Read 7 tweets

Jon Deeks

@deeksj

2 Jan

MHRA exceptional authorisation of Innova for asymptomatic individuals was issued on 22nd Dec.

This is a LIMITED approval, and the details of how and why it is LIMITED are important. It does not cover all current uses of INNOVA by Government

1/8

gov.uk/government/new…

@MHRAgovuk

Details here have been provided by the @MHRAgovuk by email. If any fact is incorrect here @DHSCgovuk @MHRAgovuk please let me know and I will change – it is a bit complicated and rather unusual.

2/8

First, approved test is called the “NHS Test and Trace COVID-19 Self-Test kit” - the LFT test in it is the INNOVA test.

Second, the test manufacturer is stated as “Department of Health and Social Care”, and not Innova.

This determines who has the duty of care and safety.

3/8

Read 9 tweets

Jon Deeks

@deeksj

21 Dec 20

What was the sensitivity and how many false positives were there from Mass Testing of University students?

Results from University of Birmingham and Universities in Scotland don’t make good reading.

SENSITIVITY 3% (not a typo)
42% of Innova positives were FALSE POSITIVES

1/15

@unibirmingham

Testing at @unibirmingham was done in our Great Hall – impressively now a testing centre. We retested a random sample of 710 Innova test negs using PCR. We haven’t heard of anybody else doing this. Preprint soon, but here are key results.

2/15

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